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John Cuthber

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Everything posted by John Cuthber

  1. "OK.. let's say I'm in a ship that accelerates away from Earth at an acceleration of 20m/s/s and then maintained that same thrust forever... " Oops! You cannot assume that because it's not possible. Please read up on relativity.
  2. What's that still doing in the news? It should have been dead and buried ages ago. http://www.channel4.com/health/microsites/M/mmr/index.html I understand that about a zillion subsequent studies have found 1 there is no statistical link; if there is an effect it is very small. 2 The rise in autism rates predates the use of the MMR vaccine- it would have had to go backwards in time to be responsible. 3 Dr Wakefield has a patent on a rival product. The word "exploitation" springs to mind here.
  3. The whole point of the titration is that you add acid until the pH is 7 then calculate the amount of NaHCO3 from the ammount of acid. Incidentally, you could take a known mass of the original mixture, heat it to convert it to the carbonae to get the weight loss and hence the amount of NaHCO3, then you could titrate this (after disolving it in water) with dilute nitric acid to get a second measurement of the NaHCO3. Then you could (using an absorbtion indicator or an ion selective electrode as an indicator) titrate with silver nitrate to get a measurement of the chloride. Then you could filter off the AgCl, wash, dry and weigh it and get a second determination of the chloride. 2 pairs of results from just one portion of mixture. And I'd still like to know what use the mass spec would be.
  4. If the membrane will let both alcohol and water through then ,in the log run, all you will get is a mixture of the 2 due to diffusion.
  5. My thermodynamics is a bit rusty but I don't think energy is the key here. If I move a Joule of energy from a cold thing to a hot thing then, overall, the system's energy is the same. On the other hand I have changed the entropy.
  6. I think the inverse square law cannot be applied to magnets (except monopoles, and they don't seem to exist).
  7. RO is great, but it's not cheap and it wastes some water. If all you need to do is kill the bugs in reasonably clean water to make it safe to drink then boiling it is the simplest option. Hard UV in the presence of air will degrade many toxins but the water needs to be filtered to make it perfectly clear first. BTW, filter candles are not the same as lighting candles.
  8. I think that the weight loss on heating would work fine. You really need to heat the carbonate very strongly to get it to decompose. an typical lab oven at a couple of hundred degrees C would decompose the bicarbonate quantitatively to the carbonate (in fact this is how high purity Na2CO3 is prepared as a lab standard). The loss of weight would give the mass of CO2 lost. The titration would work. You could also measure the chloride titrimetricaly or gravimetricaly. What I'd really like to know is what use does Sayonara think a mass spectrometer would be for this analysis. It's an enormously useful instrument for many things but, as far as I can see, this isn't one of the things it would be good for. Not least, things need to be volatile to get into a mass spec, NaCl isn't and NaHCO3 would decompose. Also, mass specs are not noted for brilliant quantitation. They are good for identification, but you know what the 2 compounds are here.
  9. Do you need a really accurate answer in wghich case you need to do some research on calorimetry or do you just need a good enough answer to help with losing weight? If it's the latter then there are tables of data like this one http://www.thecaloriecounter.com/Foods/500/5049/Food.aspx (chosen randomly from a google search; I don't know if it's any good) that you can look up.
  10. That estimate seems to be a few tens of KWHr and nothing to do with a power measurement in Megawatts. If anyone wants to find the answer it might have been measured. You need to know the energy of fracture (AKA work of fracture) for the concrete and also the area of a ton of 100 micron dust. Work of fracture is a fairly important property in engineering and concrete is pretty common so I imagine the value has been measrued. If not, you can measure it yourself.
  11. "Since you said "as far as I recall" instead of "in my opinion", I feel compelled to respond that the generally-accepted view is that this country has an extremely active and organized "far left"..." I accept that that is, as you say, the generally accepted view in your country. Like roughly 95% of the world's population I don't live in your country. I'm not sure that my opinion is not more generally representative of the world as a whole, though I accept I have done no research on this.
  12. This is probably cheating but it used to be common practice. Roast the carbonate with coke in an arc furnace to get calcium carbide then cool and add water to get acetylene. (If using coke is thought of as cheating then I think you can use hydrogen to reduce CO2 (obtained by heating or acidification of the carbonate) to give carbon monoxide which you can disproportionate to CO2 and Carbon). React the acetylene with hydrogen and a catalyst to give ethylene then add water in the presence of an acid catlayst to get alcohol. Practically speaking, you would do better to roast the carbonate to CO2, grow sugar cane in the CO2 produced and ferment it to alcohol. (and, Darkblade48, where's your sense of adventure?)
  13. The chemistry doesn't enter into it. Don't leave 600V out in the rain. (BTW, to answer the question, yes, there will be problems with electrolytic corrosion)
  14. As far as I recall, the US hasn't had a far left to be impotent or anything else.
  15. IPA is easier, and therefore cheaper, to make than n propanol.
  16. Since someone has dug up this thread I thought I'd mention that my sample of "99.9%" Gd is still magnetic (ie you can pick it up with a magnet) even when it's quite warm ie about 50C. It's a lot more strongly atracted to the magnet when it's cold.
  17. At least for the positive integers (ie the numbers we usually think of as "numbers" ) the product of any even number and any number is always even. For any 2 consecutive numbers, one of them will be even so their product will be odd. I think zero is considered to be even after all, if I divide it by 2 I get 0 and (more importantly) no remainder, so 0 and 1 multiplied together give 0 and that's even too.
  18. An interesting fact to throw into the mix. McDonalds are the world's largest distributors of children's toys (and you thought it was Santa).
  19. John Cuthber

    Stars

    Because the clouds are in the way.
  20. Actually, the whole point of a labour government is to spend money to improve things. Unfortunately we haven't had one for decades.
  21. Define "plenty" and "drastic". Actually, don't bother, it's just that your definitions won't tally with those of the people putting forward the plan. An alternative would be to simply tax these large, well established, rich businesses as businesses. The loan of a teacher or two might look very cheap by comparison.
  22. Fair point, yes they are a bit sneaky. On the other hand, as a DNA based life form I'm a bit upset that you don't like organophosphates.
  23. Pure DMSO is an odd choice (though I don't like the aftertaste you get when it ges on skin it's barely toxic). But what I'd really like to know is what is a "dishonest poison"?
  24. In the heat of the moment I'd probably try to save the 5 year old. The idea that this is much to do with evolution intrigues me. I'm no bible scholar but I bet that somewhere it would offer advice that would agree with my decision. So maybe I'm not acting on the advice of my genes, but on that from a book I have heard bits of but don't believe in. On the other hand perhaps I would just be acting on the traditional idea of "Women and children first". After the fact I'd probaly justify it in much the same terms as YT2095 but, at the time I'd not really have had time to think that through. Since I don't know exactly how I came to this decision I think it's pretty conceited of anyone to tell me how I did so. Ascribing my behaviour in a complex problem to a single molecule seems odd to say the least. Of course, whether this reactions is instinctive, religious or cultural in its origin doesn't matter. The young child is almost always the logically correct choice (anyone want to argue that I should save the Granny?) and any instinct, society or religion that decreed against it would suffer in the long term.
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